1. Field of the Invention
This invention pertains to a method and apparatus for automatically adjusting a fluid flow to have a predetermined temperature and volume flow rate, especially in applications involving residential and commercial plumbing installations such as shower and sink basin water control units.
2. Description of the Prior Art
Many methods and apparatus for the mixing and control of fluids are known. The device with which people most often come in contact is the conventional faucet or shower arrangement, wherein the temperature and volume flow rate of the effluent water are controlled through independent, manual adjustment of knobs mechanically coupled to ball valves in the hot water line and cold water line, respectively. The procedure of turning on both valves, adjusting for a desired volume flow rate, holding one's hand in the stream to sense temperature, and readjusting the knobs to obtain a desired temperature while maintaining the desired volume is so often carried out as to become reflexive. Nevertheless, the procedure can be time consuming, and a scalded hand as a result of water which is initially too hot or which is unintentionally adjusted to become too hot can be a major annoyance if not an outright hazard.
Moreover, swings in temperature due to additional demands on the water system are a familiar occurrence. In the past, however, it has been necessary simply to tolerate these changes in temperature, or to continually manipulate the hot and cold water knobs to compensate for these undesirable changes.